PLAN B analog blog

OK, let me expound on this a little bit.

The first thing we must take into consideration is the M24 is putting
out random voltages.  We cannot with certainty say it's not equally
bipolar to the Mean setting simply because it's pulling more to one
side than the other at any given time due to the nature of the
uncertainty fundamental to it's operation.  This is most evident in
slow smooth random outputs.  It will hang in the read zone for long
periods of time, sometimes it will hang in the green zone for long
periods of time. When this occurs one may think the unit isn't
operating properly when in fact it is.  What it's isn't doing is
assuring equal distribution, meaning there's no intelligence that
analyzes whether it's been positive more than it's been negative and
adjusts to distribute that more evenly.

This being said and as explained in my previous letter, the SSM 2164
does tend to pull the offset up a bit, but we're talking about a half volt. What I took into cosideration werevoltage swings from both the smooth and stepped outputs which are adequate for full panning, something i think is fair to say requires bipolar voltages to perform properly.  If you feel your voltage is too much to one side, just adjust the Mean to compensate.  A key in this is determnining what one side means - it's not to + and - voltage, it's to the + and - of the set deviation point.

Understanding how these two controls work I think will clear up much
of the confusion:

In application, the Mean pot serves as an offset, akin to the Model
14's offset pot with the addition of a second control, a VC input for
voltage control of that setting the M14 doesn't have.  The Deviation
pot opens the VCA that governs the amount of voltage, in this instance
random,  allowed from the offset set by the Mean pot.  These two work
together in determining the output attributes at any given time.

But here's a key point:  The amplitude range of the M24 is such that
with the Mean all the way down an the Deviation all the way up, the
outputs swing is such that it'll clip to the maximum rails.. a lot. 
In short, the scaling has been set so you can get more swing that
would be considered functional.  Backing the Dev down such so that the
outputs just graze these maximum limits is easily achieved.

Hope this helps,

- P


 


--- In PLAN_B_analog_blog@yahoogroups.com, "(i think you can figure
that out)" <peter@...> wrote:
>
> I'm late for a thing (jonathan Betton of Plan B is moving, we're
> having a swill with him ) I can't spend too much time right now on
> this but I will when I get back tonight.  
> 
> Nothin's wrong with your unit.  Remember, a VCA only responds to
> positive control voltages and the the SSM2167 VCA's in the M24.
> although offset internally to compensate still pull a bit heavy on the
> positive side.  Just adjust the MEAN if you want bipolar, that's a big
> reason why it's there.  Now, if it pulls more to red and green or vice
> versa - remember, this is random.  It all depends on what comes out of
> the dice at any given moment.
> 
> I'll go into more detail on this as son as I can.
> 
> - P
> 
> 
> 
> --- In PLAN_B_analog_blog@yahoogroups.com, "joshualiburdi"
> <liburdi.joshua@> wrote:
> >
> > Been trying to figure this one out for a while, maybe someone could
> > clue me in on if this is a problem or just the way this thing
> > operates. The issue is on the stepped generator half of the module.
> > When I have the Mean turned 50% the only voltages I am getting are
> > positive red voltages. The only time I get green negative voltages is
> > when Deviation is turned almost completely counterclockwise. According
> > to the graph here http://www.ear-group.net/varidev.jpg I think I
> > should be getting the full range of the module. 
> > 
> > With the Deviation fully clockwise (or 100%), the Mean has to be at
> > about 8 o' clock (or, about two ticks clockwise) before I start to get
> > negative green voltages. 
> > 
> > Any ideas?
> >
>